Allow relocation of Scrap/Choices, run time adapt BootVars
- Allow for !Scrap and Choices to be moved outside of !Boot (to !Scrap and !Choices at the same directory level). This just involves peeking to see whether they are there and using them in preference to the default position inside !Boot.
- Update BootVars to select Internet 4 or 5 support at runtime, to allow removal of
COMPAT_INET4 in future. This is somewhat of a special case since it runs before !Boot has had chance to soft load Internet 5.